The center portion of the Subi Reef runway is shown in this Center for Strategic and International Studies (CSIS) Asia Maritime Transparency Initiative January 8, 2016 satellite image released to Reuters on January 15, 2016. Photo: Reuters/CSIS Asia Maritime Transparency Initiative/Digital Globe/Handout via Reuters/File Photo

The United States should do nothing to harm China's sovereignty and security in the South China Sea, China's foreign minister told U.S. Secretary of State John Kerry, ahead of a key court ruling on China's claims in the disputed waterway.

Speaking by telephone on Wednesday, Chinese Foreign Minister Wang Yi told Kerry the United States should stick to its promises not to take sides in the dispute, China's foreign ministry said.

China hopes the United States "speaks and acts cautiously, and take no actions that harm China's sovereignty and security interests", the statement paraphrased Wang as saying.

Tensions and rhetoric have been rising ahead of a July 12 ruling by an arbitration court hearing the dispute between China and the Philippines over the South China Sea in the Dutch city of The Hague.

China is conducting military exercises around the Paracel Islands in the north of the region this week, while U.S. Navy officials said on Thursday that U.S. destroyers had been patrolling around Chinese-held reefs and islands in the contested Spratly Islands to the south.

While not close enough to be within 12 nautical miles - a so-called freedom of navigation operation that would require high level approval - the destroyers operated within 14 to 20 nautical miles of the Chinese-occupied features, the Navy Times reported.

The USS Ronald Reagan and its escort ships have also been patrolling the South China Sea since last week.

"All of these patrols are conducted in accordance with international law and all are consistent with routine Pacific Fleet presence throughout the Western Pacific," Pacific Fleet spokesman Lieutenant Clint Ramsden told Reuters.

Peaceful resolution sought

China frequently blames the United States for stirring up trouble in the South China Sea, where its territorial claims overlap in parts with Vietnam, the Philippines, Malaysia, Brunei and Taiwan.

Speaking in Beijing following a meeting with Wang on Thursday, U.N. Secretary-General Ban Ki-moon said that while he could not comment on the Philippines legal case, he called for a peaceful resolution of differences.

"I did stress to minister Wang, as I have with all other countries involved, the need to resolve their differences in a peaceful manner and to avoid any escalation or misunderstandings that could put security and development in the region at risk."

Wang repeated China's position that it also wanted a peaceful resolution, but that it would not accept forced arbitration.

"This approach will not help bring about a peaceful resolution of disputes. On the contrary, it would only escalate the disputes and tension and should be resisted by all countries and people who uphold justice."

China has accused the United States of militarizing the waterway with freedom of navigation patrols, while Washington has expressed concern about China's building of military facilities on islands it controls in the South China Sea.

U.S. officials say the U.S. response should China stick to its vow to ignore the ruling could include stepped up freedom-of-navigation patrols close to Chinese claimed islands in what is one of the world's business trade routes.

In the call initiated by Kerry, Wang also said relations between China and the United States were generally on a sound track and that the two sides should further focus on cooperation while managing their differences.

The U.S. State Department confirmed that Kerry had spoken to Wang, without providing details.

U.S. officials say they fear China may respond to the ruling by declaring an air defense identification zone in the South China Sea, as it did in the East China Sea in 2013, or by stepping up its building and fortification of artificial islands.